Hot take: The game feels good right now
I feel like we have this illusion of perfect balance. We as a community want every single character to feel like a god. In reality, if everyone is the same or "balanced" where's the variety. This game is rock paper scissors. If you're a Black Panther main, of course you're going to complain that Thing is OP. Thing mains are going to say that he dies to easily and needs a buff. Everyone sees a different side of the coin and the devs can't balance for everyone.
I think DD is the perfect character to introdouce at this time. He feels SO good to play, his kit is simple but has so much skill expression. As of currently though, it does feel like he gets lobby focused just because of how big of a target he is. Time will tell I'm sure, but maybe a size/hitbox reduction would serve him well.
I think that teamups need to feel like they actually require teamwork. Make them better, like borderline Hela/Namor, BUT require an input from both. Just imagine if H/N required both of them to aim and confirm the circle. It would feel rewarding and not like you're just forced to run namor if you have a Hela and vice versa. I think that is what the devs are trying to do with teamups, like the DD one. I like the idea of it but I hope that it actually is useful, unlike the Groot/Rocket/Jeff one.
Overall at this point the game feels a lot more fun then it did two season ago. Keep catering to tank players and I think the rest will come pretty simply.